In many layered protocols each layer has its own header surely it would be more efficient to have a single header at z front of each message with all the control in it than all these separate header why is this not done?
Answers
Answer:
Because the layers are added and removed at different steps of the transmission of the message like sending a letter: You put the message inside an envelope, the postal service might wrap up a collection of letters and unwrap the bulk near the destination so that the receiver just needs to unwrap the message. The receiver doesn’t need to know or care whether there were additional envelopes. Similarly, at every stage of delivery only ever the outermost envelope matters to the handler. This keeps things simple, efficient and secure between heterogenious machines and networks.
If you can make certain promises about how machines behave, like for instance in a trusted network, for example between machines of the same provider or with a streaming protocol or possibly a quantum networking protocol, you can reduce that overhead in different ways, while sacrificing flexibility.
Explanation: